Lens-interchangeable cameras which include a camera body and a lens barrel which can be attached and detached to and from a substantially circular opening formed on the front of the camera body are known in the art (e.g., Patent Literatures 1 and 2).
This type of camera body is provided with a plurality of (e.g., three) body-side bayonet lugs which project from the edge of the opening toward the inner peripheral side, and body-side contact portions which are connected to a battery and a controller, etc., that are installed in the camera body. On the other hand, the lens barrel is provided with a plurality of (e.g., three) lens-side bayonet lugs which project toward the outer peripheral side and lens-side contact portions which are connected to a lens drive motor and other which are installed in the lens barrel.
Upon the lens barrel being mounted to the camera body using the body-side bayonet lugs and the lens-side bayonet lugs, the body-side contact portions and the lens-side contact portions come into contact with each other to establish electrical continuity and conductivity, which allows the lens drive motor, etc., to operate using power of the battery installed in the camera body.